Initial Common Secret Key Sharing using Random Plaintexts for Short-range Wireless Communications

With the advent of radio frequency-based remote controls, we have to consider new security threats of eavesdropping and unauthorized controls in exchange for user-friendliness. Against these attacks, it is effective to encrypt and authenticate control commands. However, it will be a challenge to design how we establish a common secret key for encryption and authentication between a remote control and a controlled device. We propose new initial common key sharing protocol, which extends the over-the-air key transport in plaintext with suppressing the transmission power. Our proposed protocol increases the amount of transmission data by sharing the secret data to multiple random plaintexts, and makes it difficult for the eavesdroppers that are not located near the transmitter to obtain secret data by increasing the probability of the transmission error at the eavesdroppers. We evaluate the security level of our proposed protocol based on IEEE 802.15.4 specification, and show the relationships among the amount of transmission data, the bit error rate at eavesdroppers, and the number of trials to find the secret data through a brute force attack.